• International Journal of Reliability and Applications
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• v.12 no.1
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• pp.41-48
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• 2011

This paper considers the maintenance model suggested by Jung and Park (2010) to adopt the Bayesian approach and obtain an optimal replacement policy following the expiration of NFRRW. As the criteria to determine the optimal maintenance period, we use the expected cost during the life cycle of the system. When the failure times are assumed to follow a Weibull distribution with unknown parameters, we propose an optimal maintenance policy based on the Bayesian approach. Also, we describe the revision of uncertainty about parameters in the light of data observed. Some numerical examples are presented for illustrative purpose.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.10 no.16
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• pp.53-61
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• 1987

This study is on the Management by Policy-Deployment(MBP) a Japanese-devised management system which recently call a widespread awareness and applications among major Korean Industries. The principal nature of MBP was compared with Management by Objectives(MBO) as these two systems share similarities in basic nature. Then the major application problems of MBP encountered by the practicing managers were encountered and examined In relation to the Japanese firms organizational culture.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.259-262
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• 2005

This paper addresses the problem of protecting security policies in security mechanisms, such as the detection policy of an Intrusion Detection System. Unauthorized disclosure of such information might reveal the fundamental principles and methods for the protection of the whole network. In order to avoid this risk, we suggest two schemes for protecting security policies in Snort using the symmetric cryptosystem, Triple-DES.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.297-300
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• 2005

Especially, system security is very important in the ubiquitous environment. This paper proposes a protecting scheme for security policies in Firewall and intrusion detection system (IDS). The one-way hash function and the symmetric cryptosystem are used to make the protected rules for Firewalls and IDSs. The proposed scheme could be applied in diverse kind of defense systems which use rules.

• International Journal of Reliability and Applications
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• v.12 no.2
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• pp.131-143
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• 2011

In most of literatures of age replacement policy, the authors consider the case that a new item starts operating at time zero and is to be replaced by new one at time T. It is, however, often to purchase used items because of the limited budget. In this paper, we consider age replacement policy of a used item whose age is $t_0$. The mathematical formulas of the expected cost rate per unit time are derived for both infinite-horizon case and finite-horizon case. For each case, we show that the optimal replacement age exists and is finite and investigate the effect of the age of the used item.

• Communications for Statistical Applications and Methods
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• v.9 no.1
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• pp.21-31
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• 2002

This paper considers a Bayesian approach to determine an optimal replacement policy for a repairable system with warranty period. The mathematical formula of the expected cost rate per unit time is obtained for two cases : RFRW(renewing free-replacement warranty) and RPRW(renewing pro-rata warranty). When the failure time is Weibull distribution with uncertain parameters, a Bayesian approach is established to formally express and update the uncertain parameters for determining an optimal replacement policy. Some numerical examples are presented for illustrative purpose.

• Journal of Information Technology Applications and Management
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• v.14 no.4
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• pp.221-233
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• 2007

Which factors should influence consumer consideration to subscribe to Voice over Internet Protocol (VoIP)? Policy issues, managerial concerns, and demographic variables are possible factors. This paper discusses policy and managerial issues regarding VoIP adoption. A model that explains VoIP adoption is proposed and tested. This study analyzes a survey of 750 prospective VoIP users in Korea. The testing is accompanied by logistic regression and discriminant analysis. The results show that trust in VoIP, relative comparison of Quality to fixed service, numbering plan, satisfactions of call Quality and customer services on both fixed and mobile services have impacts on the adoption of VoIP. Implications for VoIP providers and policy makers are presented.

• International Journal of Reliability and Applications
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• v.10 no.1
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• pp.33-42
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• 2009

In most of literatures of age replacement policy, the authors consider the case that a new item starts operating at time zero and is to be replaced by new one at time T. It is, however, often to purchase used items because of the limited budget. In this paper, we consider age replacement policy of a used item whose age is $t_0$. The mathematical formulas of the expected cost rate per unit time are derived for both infinite-horizon case and finite-horizon case. For each case, we show that the optimal replacement age exists and is finite and investigate the effect of the age of the used item.

• Asian Journal of Innovation and Policy
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• v.11 no.3
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• pp.320-341
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• 2022

Empirical applications to explain criminogenic events are abundant. While much of the research in criminal studies concentrates on understanding the motivations of offenders and preventing victimization from a micro perspective, there have been recent theoretical advancements that give priority to the role of spatial factors in directly impacting crime rates. The primary purpose of this study is to investigate the empirical inference between violent crime incidence and spatial characteristics of local areas focusing particularly on spatial accessibility conditions in the areas. Applying discrete spatial econometrics models, this study reveals a significant relationship between spatial accessibility and the formation of violent crime hot spots in South Korea. Along with other variables, it is revealed that road accessibility has a clear association with violent crime hot spots. Based on the findings, this study suggests some policy implications such as effective surveillance systems, land use restrictions, and advanced street lighting.

• Journal of Broadcast Engineering
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• v.24 no.1
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• pp.105-117
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• 2019

Current Android smartphones include about 25 to 35 essential applications(unerasable) related to function and operation of the android smartphone itself and about 30 optional applications(removable) provided by carriers, Google and manufacturers. These applications were not able to be removed until the announcement of the smartphone applications pre-install guide from the government in January 2014, so there were memory limitations in installing new applications, causing consumer complaints by consuming data during the auto-update process of the pre-installed applications. After the announcement, we were able to delete optional applications but the complaints about the data consumption still did not disappear. Therefore, in this paper, we carried out the customer survey and analyzed the behavior information such as how carriers are operating pre-installed applications and what kind of applications customer prefers and how many applications customer wants to be pre-installed. And we proposed how to configure pre-install applications on smartphone for customer needs.